Image restoration processing can reproduce a high-definition image from a blurred image. In the restoration processing, however, a high frequency component of the image is enhanced, and thus noise included in the image is also significantly amplified. For this reason, in order to obtain a well-restored image, a noise reduction processing with high precision is needed before the restoration processing is performed.
Usually, examples of the noise reduction processing include a processing using a low-pass filter. In this processing, the high frequency component of the image is limited to reduce noise. An edge component included in the high frequency component is also reduced, however. As a result, the edge of the image is undesirably blurred.
Contrary to this, in the related art, a technique of performing different noise reduction processings on a flat portion of an image and an edge portion of the image has been disclosed (for example, see PTL 1 and PTL 2).